For testing iimRunner it can be useful to start it as a different user. You can use the built-in Windows RunAs command for this.
You make a shortcut that runs the following:
runas /savecred /user:localmachinename\SecondUser "iimrunner.exe"
If you use the /savecred switch Windows will store the password: The first time you do this, you will be prompted for a password. After that, you will not need to enter the password again
Note: The /savecred switch is only available in Windows XP Pro or better